At present, general-purpose waste water treatment systems include pretreatment subsystems, falling film evaporators, forced circulation crystallizers, crystal filtration subsystems, and centrifugal dehydration subsystems. Among them, it is difficult to precisely define the residence time of the crystal in the crystallizer because the particle size of the crystallizer is not uniform and unstable. In addition, due to the formation of large salt in the crystallizer, plugging often occurs in actual operation, and plugging causes the entire waste water treatment system to have a lower treatment efficiency and higher energy consumption, which is not conducive to energy conservation and emission reduction.